Muskrats as a bellwether of a drying delta.

Wetlands worldwide are under threat from anthropogenic impacts. In large protected North American areas such as Yellowstone and Wood Buffalo National Parks, aquatic habitats are disappearing and wetland-dependent fauna are in decline1-3. Here we investigate population dynamics of an indicator species in Canada's Peace-Athabasca Delta ("the delta"), a World Heritage Site. Based on population surveys, habitat mapping and genetic data from 288 muskrats, we use agent-based modeling and genetic analyses to explain population expansion and decline of the semi-aquatic muskrat (Ondatra zibethicus). Simulations quantify a large population (~500,000 individuals) following flood-induced habitat gains, with decreased size (~10,000 individuals) during drying. Genetic analyses show extremely low long-term effective population size (Ne: 60-127), supporting a legacy of population bottlenecks. Our simulations indicate that the muskrat population in the delta is a metapopulation with individuals migrating preferentially along riparian pathways. Related individuals found over 40 km apart imply dispersal distances far greater than their typical home range (130 m). Rapid metapopulation recovery is achieved via riparian corridor migration and passive flood-transport of individuals. Source-sink dynamics show wetland loss impacts on the muskrat metapopulation's spatial extent. Dramatic landscape change is underway, devastating local fauna, including this generalist species even in a protected ecosystem.

Gut microflora may facilitate adaptation to anthropic habitat: A comparative study in Rattus.

Anthropophilic species ("commensal" species) that are completely dependent upon anthropic habitats experience different selective pressures particularly in terms of food than their noncommensal counterparts. Using a next-generation sequencing approach, we characterized and compared the gut microflora community of 53 commensal Rattus rattus and 59 noncommensal Rattus satarae captured in 10 locations in the Western Ghats, India. We observed that, while species identity was important in characterizing the microflora communities of the two Rattus hosts, environmental factors also had a significant effect. While there was significant geographic variation in the microflora of the noncommensal R. satarae, there was no effect of geographic distance on gut microflora of the commensal R. rattus. Interestingly, host genetic distance did not significantly influence the community in either Rattus hosts. Collectively, these results indicate that a shift in habitat is likely to result in a change in the gut microflora community and imply that the gut microflora is a complex trait, influenced by various parameters in different habitats.